Cheese analogs are conveniently prepared from milk solids i.e., casein, which is precipitated from skim milk either by acid precipitation or enzymatic coagulation.
Cholesterol or cholest-5-en3.beta.-ol is the principle steroid of higher animals. It is found in all body tissues, especially in the brain, spinal chord and in animal fats and oils. Cholesterol, which is known to be the precursor of bile acids, steroid hormones and pro-vitamin D3, is basically obtained by the body from the diet even though a major portion needed for normal mody functions is endogenously snythesized. Epidemiological and nutritional studies have shown that an elevation of cholesterol in blood plasma is one of the more important risk factors leading to coronary heart disease. For this reason, medical authorities advise patients with elevated blood serum cholesterol levels and whose family history includes early deaths from arteriosclerosis to restrict fat intake and in particular, cholesterol, and to avoid foods which are generally known to contain high cholesterol levels. Cheese is known to contain cholesterol and should be avoided by individuals on a cholesterol restricted diet. Cheese analogs which are prepared from casein or caseinates still contain cholesterol because of relatively large amounts of cholesterol present in the casein.
Casein is a mixture of phosphoproteins naturally occuring in milk. This material contains all of the common amino acids and is particularly rich in essential amino acids. Due to its desirable nutritional balance, casein is very useful as an ingredient in many food products, particularly cheese analogs. We have found that cholesterol distributes unevenly between casein and whey when the former is precipitated from skim milk. Thus if one starts with 100 ml of skim milk and subjects it to the conventional process of acid precipitation of casein, 36.3% of the colesterol is found in the liquid phase, i.e. whey, and 48.8% in the solid phase, i.e., casein. Moreover, it has been found that cholesterol is associated with the casein in some unknown way and is not removed by solvent extractive means compatible with food processing procedures.
Cheese analogs containing less than 21/2 mg/100 gm or 2.5 mg(%) cholesterol are regarded as being substantially cholesterol free and can be marketed as such. Thus, while it is an object of this invention to provide a mehtod for producing casein having a cholesterol content of below about 10 mg(%), a preferred embodiment involves producing casein containing less than 7 mg(%) cholesterol which, when mixed with the other ingredients, will provide a cheese analog containing less than 2.5 mg(%) cholesterol.